Ok I'd actually be thinking the opposite. I'd think that it might be beneath someone of the upper classes to serve as a runner or messager. I'd think the right man for the job would be a kern who was particularly swift and nimble. Also I think that if the messager was a person of the upper classes he would be on horseback. Anyway this is all just my opinion, and I could be way off.

I doubt that the messenger is a low class kern, since his name, Donolle O'Breane, appears right in the woodcut to identify him. he may have been a Captain of Kern or middle ranking person. Remember, even chietains and gallowglass are desribed as dressing in this manner also.

Javelins do have cords, but they are located towards the center to facilitate balance when throwing, at least that is where I have placed mine, and the Painting of Lee, Captain of the Queens own Kern, shows the cord in the middle also. I'm not convinced that this is a javelin, but with thorns on it, I'm not sure what it is. I had always just assumed it was a walking stick.

Finn O'BreananWood Kerne

"...The O'Brennans, a sept of thieves without any right or title, ... were a perpetual disturbance to the peace of the county,"

Thinking on this I reckon the only way to be sure of the person (And therefore the likely armament or not) is to look for evidence of accounts of messengers/envoys and see what they are depicted as carrying/wearing...even with the right library access it could be quite time consuming!